Tamsyn Waterhouse learned to fly as a child under her father's wing in his 1968 Cessna 150 -- a fuel-leaking, scrappy plane that constantly tested her abilities and confidence.

"One afternoon I had to wedge myself under the instrument panel in order to re-solder an electrical connection, with a piece of scrap aluminum shielding my chest from dripping solder," said Waterhouse, 32, who works for Google in San Francisco.

She easily got her private pilot's license in 2003, but nothing prepared her for the hurdles the Federal Aviation Administration threw at her in 2009, when she tried to get her airman's medical certificate renewed.

Waterhouse is transgender, and the FAA required that she go through a battery of psychological tests -- five in all -- that would "take a couple of days of my time and cost in the several-thousand dollar range."

Upset and feeling "lost," she fought that policy, clearing the path for other transgender pilots, to spare them the onerous testing.

"It's a big first step," said Waterhouse. "Someday I hope that all pilots can be treated fairly with regard to gender," she said.

The change reflects a growing trend in government and the courts to eliminate discrimination against those who are lesbian, bisexual, gay and transgender. Most recently, the Employment Equal Opportunity Commission ruled that transgender people were covered under Title VII's employment discrimination protections.

And the Department of Health and Human Services has now specifically banned discrimination against those who are transgender in federally funded health care programs.

The previous policy was based on "outdated stereotypes that someone who changed their gender had something mentally wrong with them," said Matt Wood, the Transgender Law Center lawyer the who took Waterhouse's case.

"Anyone who is transgender has to undergo medical or psychological treatment to help their external body match their internal sense of self," said Wood. "That is no different from any other kind of medical condition, and the FAA is concerned about medical conditions, because they fly planes."

The policy now states that no neurocognitive testing is required unless it is clinically indicated.

"Basically, the doctor looks to see if [the pilot] is color blind and can pass all the medical things and if the therapist says the transition had gone well or was a success," Wood said. "It's no longer carte blanche."

Wood said he was "thrilled" with the new policy and also with Waterhouse, who was "extremely successful in her career, extremely patient and really understood this was a policy and not a lawsuit case."

A pilot's license has two parts. The first is the actual pilot certificate, which establishes identification and privileges and never expires. The second is the airman's medical certificate, which at the private pilot level, must be renewed every five years.

"Ordinarily, this is very simple," Waterhouse said. "You find an aviation medical examiner and give them about $100 and they give you a physical and vision and hearing tests, and if you're in good shape they can issue your medical certificate right there."